5 ms·

Can someone explain how these tracks were preserved on a sand dune? As far as I know a sand dune moves constantly. I can't imagine tracks would last a day. Lo

by thdrdt 6y ago

Can someone explain how these tracks were preserved on a sand dune? As far as I know a sand dune moves constantly. I can't imagine tracks would last a day. Looking at the tracks it looks more like they were made in mud and later covered by sand dunes?

jcims 6y ago
Maybe the low parts near water? It had to be wet to capture what appear to be claw marks.
rement 6y ago
The authors of the paper actually describe their hypothesis for how it occurred [0]. Basically perfect conditions were required to preserve them. In short the first tracks were made in dry sand, eroded a little, moistened by fog, dew, or light rain, and then covered by dry sand again. The second tracks were made through the dry sand into the moist layer which was then crusted over with calcite and covered. Only the toe markings from the second tracks were preserved. [0] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237636#sec014 https://journals.plos.org/plosone/article?id=10.1371/journal...
- austincheney 6y ago
  The presence of a layer composed of a compressed calcium based salt suggests earth that eventually became covered by ocean. Calcium deposits make for fantastic preservatives. See caliche and Llano Estecado as examples. * https://en.m.wikipedia.org/wiki/Caliche https://en.m.wikipedia.org/wiki/Caliche * https://en.m.wikipedia.org/wiki/Llano_Estacado https://en.m.wikipedia.org/wiki/Llano_Estacado
lmilcin 6y ago
It might be something as silly as change of wind that brought dust instead of sand or maybe different type of sand. Basically anything that covers the fresh print with a layer that is different enough chemically or physically that will then cause the layers to develop/preserve a boundary that can then break clean off millions of years later after everything is pressed/mineralized/whatever other processes happened.

by thdrdt 6y ago

jcims 6y ago

Maybe the low parts near water? It had to be wet to capture what appear to be claw marks.

rement 6y ago

The authors of the paper actually describe their hypothesis for how it occurred [0]. Basically perfect conditions were required to preserve them. In short the first tracks were made in dry sand, eroded a little, moistened by fog, dew, or light rain, and then covered by dry sand again. The second tracks were made through the dry sand into the moist layer which was then crusted over with calcite and covered. Only the toe markings from the second tracks were preserved. [0] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237636#sec014 https://journals.plos.org/plosone/article?id=10.1371/journal...

austincheney 6y ago
The presence of a layer composed of a compressed calcium based salt suggests earth that eventually became covered by ocean. Calcium deposits make for fantastic preservatives. See caliche and Llano Estecado as examples. * https://en.m.wikipedia.org/wiki/Caliche https://en.m.wikipedia.org/wiki/Caliche * https://en.m.wikipedia.org/wiki/Llano_Estacado https://en.m.wikipedia.org/wiki/Llano_Estacado

lmilcin 6y ago

It might be something as silly as change of wind that brought dust instead of sand or maybe different type of sand. Basically anything that covers the fresh print with a layer that is different enough chemically or physically that will then cause the layers to develop/preserve a boundary that can then break clean off millions of years later after everything is pressed/mineralized/whatever other processes happened.